GB2265696A

GB2265696A - Gun with regerative injection of liquid propellant

Info

Publication number: GB2265696A
Application number: GB8913916A
Authority: GB
Inventors: Jean-Marie Poussard
Original assignee: Thomson Brandt Armements SA
Current assignee: Thomson Brandt Armements SA
Priority date: 1988-06-17
Filing date: 1989-06-16
Publication date: 1993-10-06
Anticipated expiration: 2009-06-16
Also published as: GB2265696B; DE3919761A1; DE3919761C2; FR2677741B1; GB8913916D0; FR2677741A1

Description

2-5-165696 Gun with regenerative injection of liquid propellant The

present invention relates to a gun using a liquid pro pulsive charge such as a liquid propellant whose injection is performed during firing by means of a piston exterior to the barrel.

The propulsive charge used in guns is conventionally in the form of a solid whose volume is set at the factory, taking into account the performance that the projectile must have.

In general, this volume is modular so that it can be adjusted by the operator prior to firing as a function of the objecti ves to be hit. This operation is carried out manually and ta kes consequently a certain time, which impairs the efficiency of the weapon system during combat.

To remedy this disadvantage, the applicant proposed in its French patent application NO 88 07539 filed on June 7, 1988 to use a liquid propulsive charge, that can be easily and rapidly adjusted in an automatic manner.

gr or a ent application, there is provided between the In this a I gun barrel and a moving breech an annular space forming a re servoir chamber for the liquid propulsive charge. The end of the barrel includes means for injecting the liquid charge from the annular chamber to the combustion chamber when, during firing, the breech moves back with respect to the barrel, which tends to reduce to zero the volume of the reservoir chamber. This approach allows to adjust automatically and very rapidly the volume of the liquid charge, which permits to match each round to the desired performance and to the type of munition being used.

However, this approach with a moving breech may cause problems of construction and of bulkiness.

An object of the present iiivention is to remedy these dis-advantages by providing a barrel-breech assembly forming one piece, the injection of the charge being performed by means of an annular piston.

According to the present invention, there is provided a gun using a liquid propulsive charge, comprising a barrel having an outer surface and an nzner surface, in tended to receive a projectile; a breech closing said barrel at one of its ends and having a sidewall with an inner surface surrounding said end of the barrel; a combustion chamber for said charge delimited in particular by said breech and the rear of said projectile; a front wall solid with said barrel on its outer surface and delimiting with said inner surface of the breech and said outer surface of the barrel an annular space; an injection chanber dis posed inside said annular space; an annular Diston sliding in a watertight manner in said annular space to close said injection chamber; means for loading said propulsive charge into said injection chamber from an exterior reservoir; means for injecting said propulsive charge from said injec tion chamber to said combustion chamber during firing, said injection means being carried by said annular piston; and communication means between the portion of said annular space behind said Diston and said combus-tion chamber.

Other objects, features and advantages of the present in vention will become apparent from the following detailed des cription of preferred embodiments given as a non-limitative 3 - example with reference to the accompanying drawings, in which - Figure 1 shows a cross-sectional view of Dart of the gun according to a first embodiment of the present invention; - Figure 2 shows the part of the gun of Figure 1 at the completion of propellant injection; - Figures 3a and 3b show in elevation view and in crosssection the injection piston of the part of the gun illustrated in preceding Figures; - Figures 4 and 5 show a further embodiment of the gun of the present invention and - Figures 6a and 6b are schematics of an element of the gun of the invention.

In these different Figures, like reference numerals denote like elements.

As already mentioned, Figures 1 and 2 show, in cross-sec- tional view, a first embodiment of part of the gun of the present invention, Figure I showing the configuration of the gun during the loading of the projectile, and Figure 2 showing its configuration after ejection of this projectile.

In these Figures, the barrel 1 of the gun, as well as its breech 2, are partially shown. The breech 2 includes a moving part 21 called a wedge, to allow the introduction of the munition, a sidewall 22 with a diameter substantially larger than that of the barrel 1, the breech 2 thus forming a bulge at the rear end of the barrel, and a front wall 23 joining the breech 2 to the barrel 1 that form a one-piece assembly. Inside the barrel, a projectile 3 is shown introduced into the gun at the breech, the wedge 21 being then removed. The space between the rear of the projectile 3 and the bottom of the breech 2 (wedge 21) forms the combustion chamber in which the propulsive charge burns in emitting gases causing the ejection of the projectile.

Between the breech wedge 21 and the projectile 3, there is disposed an igniter cartridge 14 (Figure 1) whose role is described hereinafter.

Between the inner surface 24 of the sidewall 22 of the breech, the inner surface of the wall 23, the outer surface 11 of the end of the barrel 1 and the bottom 25 of the breech 2 there is defined an annular space communicating with the combustion chamber 7 either by an annular orifice 26 (Figures 1 and 2) or by openings as this will be seen later. An annular piston 9 is disposed in the annular space thus delimited and defines an injection chamber 5 for the liquid propulsive char ge, for example a liquid propellant.

In addition, the breech 2 is connected to fully conventio nal restraining and restoring means (not shown) intended, as known, to restrain its motion and to return it to its initial position.

The gun according to the present invention further compri ses means for injecting the liquid charge into the injection chamber 5, these means being denoted as a whole by 6. They are, for example, formed by a passage 61 in which a valve 62 is introduced. The propellant is stored in an outer reservoir (not shown).

In the embodiment shown in the Figures, the piston 9 in cludes means, denoted as a whole by 8, for injecting the li quid charge into the combustion chamber 7.

These means are formed, for example, by one or more pas sages 81 in which one or more valves 82 are disposed.

The injection means can, for example, be of the type - described in the French patent application NI 2 604 247.

They can also be implemented in the form shown in Figures 6a and 6b.

These means, 82, are of the valve type. They essentially include a moving part 83 closing the passage 81 under the ac tion of a spring 84, as shown in Figure 6a.

When the pressure builds up in the injection chamber 5, it drives back the part 83 (Figure 6b) thus freeing the passage 81 and permitting the liquid charge to pass to the combustion chamber through openings provided in the body of iDart 83.

The piston 9 slides in a watertight manner in the annular space forming the chamber 5.

To obtain a differential pressure (and consequently a pro pellant injection) between the combustion chamber 7 and the injection chamber 5, the piston 9 (see also Figures 3a and 3b) includes a number of rods 90, for example four in the case shown, that slide in a watertight manner in corresponding bo res provided in the front wall 23 of the breech.

The operation of the gun of the present inven tion is as follows:

In a preliminary step, the projectile 3 is introduced into the barrel 1. The projectile includes an igniter cartridge 14. This igniter cartridge supported by a metal lipped bottom or by a burnable case is separated from the munition during the introduction of the latter into the breech, then maintain ed by the bottom of the chamber and wedged up by the breech at the time of firing. In case of need, the ejection of this minibase can take place after firing in the same way as the ejection of the bases currently used in guns.

The propellant is introduced into the injection chamber through the means 6. The propellant is introduced under pressure and the valves 82 being closed, they maintain in the chamber 5 the propellant that drives the annular piston 9 back to its extreme position shown in Figure 1. The feed pressure of the propellant in the injection chamber 5 can be, for exam ple, between 10 and 30 bars, which allows a rapid filling of the injection chamber.

The ignition of the cartridge 14 results in a pressure buildup in the combustion chamber 7 and consequently the ini tiation of the forward motion of the piston 9 thanks to the existing differential pressure since a portion of the front surface of the piston is submitted only to the atmospheric pressure (front surface of the rods 90). This motion increases and the pressure in the propellant,/causes the opening of the val ves 82 that permit the injection of the propellant into the combustion chamber 7. When coming into contact with the hot ignition gases, the injected liquid self-ignites, the pressure ouilds up, the projectile accelerates, and the piston 9 conti nues to compress the propellant. The process of regenerative injection is thus initiated.

The piston 9 moves forward until it comes to rest on the wall 23 (Figure 2), which achieves the injection of the tota lity of the liquid charge, the pressure of the propellant in the injection chamber 5 being always higher than the pressure in the combustion chamber 7. Of course, there can be provided, known means, such as the arrangement of the facing surfaces, to substantially reduce the stresses induced by the impact of the piston against the wall 23.

The injection cross sections, taking into account the weights of the projectile to be launched, are optimized to obtain the highest possible muzzle velocity for the lowest maximum pressure.

Figures 4 and 5 show a variant of the gun according to the present invention, in which there is provided a simple means for adjusting the volume of the propulsive charge being used.

Numerous elements of the embodiment shown in Figures 1 and 2 are used here and will not be described in more detail.

In this embodiment, the barrel 1 and the breech 2 are not made in one piece and are assembled by a threaded sleeve 16 maintaining the breech 2 against the end of the barrel 1. The latter includes a front wall 23 on which rests the inner col lar of the sleeve 16 screwed on the front end of the breech so as to maintain the rear end of the barrel 1 resting on the bottom 25 ofthe breech 2. It is also possible to devise a front wall 23 forming one piece with the breech and no longer with the barrel without going beyond the scope of the present invention. As previously, there is defined an annular space that, with the piston 9, forms an injection chamber 5. How ever, the piston 9 is not in direct contact with the inner surface of the sidewall 22 and is disposed inside a sleeve 17 whose position is adjustable within the annular space and which has at its rear end a collar 171 serving as a stop for the piston 9. The sleeve 17 can slide inside the breech 2 who se inner diameter is larger than the outer diameter of the front wall 23 in order to provide a sliding space 20 for the sleeve 17.

The displacement of the sleeve 17 is controlled by a threa ded ring 18 screwed on a thread provided on the outer surface of the sleeve 17. This threaded ring 18 has on its outer sur face teeth cut to cooperate with a worm screw 19 so as to be driven in rotation by this worm screw. The latter is itself driven by a motor of any suitable type (electric, hydraulic, etc.) or can even be rotated manually.

Thus, by adjusting the position of the sleeve 17, it is possible to adjust the piston stop that will stop the piston 9 during filling.

Figures 4 and 5 show two different adjustments of the slee ve 17 that consequently determine two different volumes of the injection chamber 5.

8 - The filling system described above, easily automatized, is characterized in that the propellant does not fill a pre determined volume (with the risk of air, combustion gases, etc. present in it) but instead creates itself the volume it needs.

The propellant fed under pressure drives the piston to the position set by the position of the sleeve 17.

The quantity of propellant is thus matched each time to the desired performance and to the type of munition being used.

It should be noted that here the communication between the annular space 5 containing the piston 9 and the combustion chamber 7 is ensured by the openings 12 distributed at the end of the barrel 1. Furthermore, the bores in which the rods slide are vented by vent holes (not shown).

Thus the system described allows firing with "intermedia te" charges and covers the ranges usually achieved by the mu nitions used in the powder-type guns.

It is clear that also in the embodiments shown in Figures 1 and 2, it is possible to adjust the volume of the liquid charge, for example by means of adjustable stops attached to the bottom of the breech 2.

Thanks to the automatiZ2tion of the propellant filling and to the loading of the projectile at the breech, a high firing rate is achieved while retaining the conventional pro cess of breech-loading of the solid-propellant guns. In addi tion, the system of the present invention permits firing projectiles of various types and weights, and this even in the same series of firings without any particular adjust ment other than that of the volume of the liquid charge, as well as firing a given munition with any desired charge, the refore with various ranges. This system further allows, thanks to the regenerative injection of propellant during firing, - 9 a very flat pressure buildup curve to be obtained and, therefore, all other things being equal, very high maximum muzzle velocity/pressure ratios.

Finally, all charge adjustment operationa can be programmed and remotely controlled by an operator at a control cons o I e.

It is understood that the embodiments described above do not in any way limit the present invention.

- 10

Claims

1. A gun using a liquid propulsive charge, comprising: - a barrel having an outer surface arid an inner surface, intended to receive a projectile; - a breech closing said barrel at one of its ends and having a sid!wall with an inner surface surrounding said end of the 10 barrel; - a combustion chamber for said charge delimited in particular by said breech and the rear of said projectile; - a Front wall solid with said barrel on its outer surface and delimiting with said inner surface of the breech and said 15 outer surface of the barrel an annular space; - an injection chamber disposed inside said annular space; - an annular piston sliding in a watertight manner in said annular space to close said injection chamber; means for loading said propulsive charge into said injec20 tion chamber from an exterior reservoir; - means for injecting said propulsive charge from said injec tion chamber to said combustion chamber during firing, said injection means being carried by said annular piston; and communication means between the portion of said annular spa25 ce behind said piston and said combustion chamber.

2. A gun as claimedin claim 1, wherein said annular piston carries, toward the injection chamber, at least one rod extending parallel to the axis of said barrel and sliding in a wa30 tertight manner in corresponding bores provided in said front wall so that the front side of said rods is exposed to a pres- - 11 sure lower than the pressure in said injection chamber.

3. A gun as claimed in claim 1 or claim 2, wherein after .. . .............

initiation of the displacement of said piston by an igniter cartridge, said piston movesin the direction of the reduction of volume of said injection chamber under the ac,ion of the differential pressure applied to said piston until the totality of the liquid propulsive charge contained in said injection chamber has been injected into said combustion chamber and said piston comes to rest on said front wall of said injection chamber.

4. A gun as claimed in any one of claims 1 to 3, wherein there is provided means for limiting in an adjustable manner the stroke of said annular piston during the loading of said injection chamber.

5. A gun as claimed in claim 4, wherein said means for limiting said stroke of the piston comprise a first sleeve capable of sliding on the outer surface of the annular space containing the injection chamber and including an inner collar serving as a stop for said piston that slides in a liquid-tight manner between the inner surface of said sleeve and the outer surface of said barrel, and control means to control the position of said sleeve.

6. A gun as claimed in claim 5, wherein said control means comprise a worm screw and a ring having on its inner surface a thread cooperating with a thread on the outer surface of said sleeve and, on its outer surface, teeth cut to cooperate with said worm screw so that this worm can rotate said ring to displace the sleeve.

7. A gun as claimed in claim 6, wherein said worm screw is driven by a motor.

8. A gun as claimed in claim 6, wherein said worm screw is driven by a hand-operated system.

g. A gun as claimed in any one of claims 5 to 8, wherein said front wall has an outer diameter smaller than that of the inner surface of the sidewall of said breech, and wherein said gun comprises in addition a further threaded sleeve screwed on said sidewall and having an inner collar resting on said front wall to assemble said breech with said barrel, said first sleeve being capable of sliding between said inner surface of-the sidewall of said breech and the peripheric outer surface of said front wall. 10. A gun using a liquid propulsive charge and substantially as hereinbefore described and as shown in Figures 1, 2, 3a and 3b or Figures 4 and 5 of the accompanying drawings. 11. A gun using a liquid propulsive charge and as claimed in claim 1 and having injection means substantially as hereinbefore described and as shown in Figures 6a and 6b of the accompanying drawings.

3. A gun as claimed in claim 2, wherein said lower pressure is the atmospheric pressure.

4. A gun as claimed in claim 2, wherein said injection means include at least a passage extending through said piston from the injection chamber to the combustion chamber, and a valve associated with each passage, normally closed when the pressu- re in said injection chamber is the loading pressure for said liquid charge, and opening for pressures in said injection chamber reaching a value higher than said loading pressure.

5. A gun as claimed in claim 2, wherein after initiation of the displacement of said piston by an igniter cartridge, said piston moves in the direction of the reduction of volume of said injection chamber under the action of the differential pressure applied to said piston until the totality of the liquid propulsive charge contained in said injection chamber has been injected into said combustion chamber and said piston comes to rest on said front wall of said injection chamber.

6. A gun as claimed in. any of claims 1 to 5, wherein there is provided means for limiting in an adjustable manner the stroke of said annular piston during the filling of said injection chamber.

7. A gun as claimed in claim6, wherein said means for limiting said stroke of the piston comprise a sleeve capable of sliding on the outer surface of the annular space containing the injection chamber and including an inner collar serving as a stop for said piston that slides in a watertight manner between the inner surface of said sleeve and the outer surface of said barrel, and control means to control the position of said sleeve.

8. A gun as claimed claim 7, wherein said control means comprise a worm screw and a ring having on its inner surface a thread cooperating with a thread on the outer surface of said sleeve and, on its outer surface, teeth cut to cooperate with said worm screw so that this worm can rotate said ring to displace the sleeve.

0 ,, A gun as claimed in claim 8, wherein said worm screw is driven by a motor.

10. A gun as claimed in claim 8, wherein said worm screw is driven by a hand-operated system.

11. A gun as claimed in claim 7, wherein said front wall has an outer diameter smaller than that of the inner surface of the sidewall of said breech, and wherein said gun comprises in addition a threaded sleeve screwed on said sidewall and' having a inner collar resting on said front wall to assemble said breech with said barrel, said sleeve being capable of sliding between said inner surface of the sidewall of said breech and the outer side of said front wall.

12. A gun using a liquid propulsive charge and substantially as hereinbefore described and as shown in Figures 1, 2, 3a and 3b or Figures 4 and 5 of the accompanying drawings.

13. A gun using a liquid propulsive charge and as claimed in claim 1 and having injection means substantially as hereinbefore described and as sho, .,,n in Figures 6a and 6b of the accompanying drawings.

Amendments to the claims have been filed as follows 1 A gun operable to use a liquid propulsive charge, comprising: - a barrel having an outer surface and an inner surface, intended to receive a projectile; - a breech structure enclosing said barrel at one of its ends and having a sidewall with an inner surface surrounding said one end of the barrel, said breech structure and said barrel being integral or being held together to form a barrel-breech assembly; - a combustion chamber for said charge delimited in use of the gun by said breech structure, the rear of a projectile received within the barrel and the rear of the barrel; - a front wall solid either with said barrel on its outer surface or with said sidewall on its inner surface and delimiting with said inner surface of the sidewall and said outer surface of the barrel an annular space; - an injection chamber disposed inside said annular space; - an annular piston which is a sliding fit in a liquid- tight manner in said annular space to close said injection chamber, said annular piston carrying at least one rod which extends toward the injection chamber parallel to the axis of said barrel and which slides in aliquidtight manner in corresponding bores provided in said front wall so that the end of the or each said rod remote from said annular piston is exposed to a pressure lower than the pressure in said injection chamber; - means for loading said propulsive charge into said injection chamber from an exterior reservoir;, - means for injecting said propulsive charge from said injection chamber to said combustion chamber during firing, said injection means being carried by said annular piston which moves towards said front wall during firing because of the differential pressure applied to it, and including at least one passage extending through said piston from the injection chamber to the combustion chamber, and a valye associated with each said passage, normally closed when the pressure in said injection chamber is the loading pressure for said liquid -- W 1 charge, and opening for pressures in said injection chamber which exceed said loading pressure; and - communication means between the portion of snid annular space bghind said piston and said combustion chamber. 2. A gun as claimed in claim 1-. wherein said lower pressure is the atmospheric pressure.